By now you’ve probably heard of bisphenol-A, commonly referred to as BPA. It’s a chemical used in plastics and food containers, and is often found in the thermal paper used to make receipts, bus, plane and train tickets and other products. BPA helps make dyes bind to the paper, and make the printing more visible.

Many researchers are concerned about the health effects of BPA because it is an endocrine disruptor, interfering with proper function of hormones like estrogen. Animals studies have linked it to a number of concerning health effects, including abnormal brain function and sexual development.

Though BPA in plastics has borne the brunt of public and media attention, it may be the paper that is most worrisome: People who handle receipts have elevated levels of the chemical in their urine and blood, according to a paper published in JAMA in February. And a new study published today in the journal PLOS ONE has found that BPA is absorbed more quickly and extensively when people apply hand sanitizers before handling receipts.

That’s because hand sanitizers (as well as other cosmetic products like hand lotions) contain chemicals the make the skin more permeable to various substances, including BPA, says study author and University of Missouri researcher Frederick vom Saal. The study found that hand sanitizers could increase the absorption of BPA into the body by a factor of 100 or more.

The researchers first observed shoppers at fast-food restaurants and other businesses in Columbia, Missouri, noticing that in the real world, people often used hand sanitizer before touching receipts. Using hand sanitizer is “a behavior millions of people engage in every day,” vom Saal says.

Scientists then asked some volunteers in the lab to handle receipts with dry hands, and others to do so shortly after using Purell brand hand sanitizer. They found that those who used the Purell absorbed tens of times more BPA from the receipts than those without. In another experiment, subjects used Purell before handling receipts and subsequently eating french fries, as the scientists observed happening in real-world fast-food joints. This also greatly increased blood serum and urine levels of BPA.

“This [study] provides a compelling case that this is a common route through which we are exposed every day” to BPA, says Patricia Hunt, an expert on BPA at Washington State University who wasn’t involved in the research.

Overall, using hand sanitizer before handling receipts led to an average increase of seven micrograms per liter of BPA in the blood serum of participants. The resulting blood levels of BPA were “well within the range wherein the risk for a whole range of nasty conditions, from type II diabetes to angina and heart attacks to obesity and liver abnormalities” is increased, vom Saal tells Newsweek.

That’s not to say that if you douse your hands with Purell and handle a receipt one time you’ll see long-lasting consequences—but repeated high exposure of this nature could lead to real harm, he suggests.

This paper shows how “hand sanitizer opens up your skin to allow BPA to get right in,” says Laura Vandenberg, who studies endocrine disruptors at the University of Massachusetts-Amherst, who wasn’t involved in the study.

That is “shocking” in the sense that “this is not on the radar of regulatory agencies” tasked with keeping us safe from BPA, she tells Newsweek.

But then again, it’s not that surprising, since it’s well-known that small lipid-soluble chemicals like BPA can be absorbed by the skin, and can be taken in more easily in the presence of some of the substances found in hand sanitizer and other cosmetics like lotions and moisturizers, says vom Saal. These permeability-aiding chemicals include isopropyl myristate, propylene glycol and ethanol.

The U.S. Food and Drug Administration and the Environmental Protection Agency haven’t addressed the question of absorption of BPA through the skin, vom Saal says, and currently only think of the chemical as being absorbed through food in the gastrointestinal tract. But this and other studies have shown that significant quantities can come in through the skin.

The EPA wrote in an email to Newsweek that it “is not in a position to comment on the study,” in part because it “doesn’t deal with alternatives” to BPA—but it’s not clear why that is a reason for not commenting. In a January 2014 report [PDF], the EPA evaluated the use of the substance and other chemical options in receipts and concluded that there were no safe alternatives to BPA, suggesting that “decision-makers may wish to consider alternative printing systems.”

The report also suggested that BPA isn’t safe, either, stating that the chemical presents a high hazard to “developmental” human health (this designation, according to the EPA refers to a substance’s “risk to human development, growth, survival and function because of exposure prior to conception, prenatally, or to infants and children.”)

That study found BPA in 44 percent of the receipts tested and an alternative called bisphenol-S (BPS) in 52 percent. Studies suggest BPS may have many of the same health concerns as BPA.

“Based on FDA's ongoing safety review of scientific evidence, the available information continues to support the safety of BPA for the currently approved uses in food containers and packaging,” she adds.

Though some would debate you on it, it stands to reason you might consider BPA safe if you only address exposure through food; about 99 percent of the chemical ingested is rather quickly processed and eliminated by the liver, vom Saal says.

But as this and other studies make clear, BPA can be absorbed through the skin, in significant quantities. BPA absorbed this way lasts longer in the blood and isn’t immediately processed by the liver in the same way as when it is ingested.

“This is one of those nightmare stories where you're finding out a very commonly used [chemical] is a ubiquitous environmental contaminant, which poses quite a serious health risk,” vom Saal says.